1. Field of the Invention
Aspects of the present invention relate to a Space Division Multiple Access (SDMA) technology of transmitting a signal by using a plurality of antennas, and more particularly, to a system and method of allocating a wireless resource for an SDMA communication in order to apply an additional scheme to a beam-forming scheme for an SDMA and establish an optimized SDMA communication environment.
2. Description of the Related Art
Recently, research is actively under way in order to provide various multimedia services including a voice service in a wireless communication environment, and support a high-quality and high-speed data transmission. A technology of a Multiple Input Multiple Output (MIMO) system using a channel of a space area has been rapidly developed as a part of research.
Many people desire a high-speed wireless communication service, however, many problems exist in providing or using the high-speed wireless communication service in the wireless communication environment. In particular, a limit exists in increasing a data rate in a communication environment using a wireless channel since multipath fading, selective frequency fading, various communication barriers, and the like, exist. Representative technologies for overcoming the limit are a multi-antenna technology and a signal relay technology.
The multi-antenna technology is a technology of increasing reliability of a signal transmission and acquiring a high-speed data rate by transmitting a signal using a plurality of antennas. Also, a space diversity technology of transmitting the signal via the plurality of antennas can increase reliability of a received signal. In particular, a technology of transmitting different signals to multiple users via the plurality of antennas is referred to as a Space Division Multiple Access (SDMA) technology. The SDMA technology increases a capacity of an entire system by efficiently using a wireless resource.
Beam-forming of the signals transmitted via the plurality of antennas using the SDMA technology are performed via a precoding scheme according to a wireless channel state. Specifically, interference generated between wireless channels can be reduced by appropriately precoding a data stream according to the wireless channel state. For example, a mobile terminal feeds back Channel State Information (CSI) for a wireless channel generated between the mobile terminal and a base station to the base station in which the plurality of antennas is installed, and the base station performs optimized beam-forming using the fed-back CSI. Also, the wireless resource is consumed so that the CSI may be fed back to the base station.
Also, the signal relay technology is a technology of relaying a signal generated from a source node via a relay node existing between the source node and a destination node. A power amplification relay scheme as a representative relay scheme improves a Signal-to-Interference and Noise Ratio (SINR) or a data rate since the relay node amplifies a power of a source signal and transmits the source signal to the destination node. Also, in this case, the wireless resource is consumed when the relay node relays the signal.
Also, since a beam-forming technology for an SDMA and the signal relay technology are respectively researched as separate technologies, the wireless resource cannot be efficiently used. For example, even though the relay node is not necessarily used when the channel state of the wireless channel generated between the source node and the destination node is favorable, a high data rate and a high SINR can be acquired via the appropriate beam-forming. However, in this case, consuming many wireless resources for a signal relay can be wasteful.
Also, when a desired data rate and a desired SINR can be achieved with only a slight signal amplification since the relay node and the destination node are located within a short distance, increasing a feedback amount for the CSI can waste the wireless resource despite reducing a necessity that the destination node feeds back the voluminous CSI to the source node so that the source node may perform the beam-forming.
Accordingly, a system and method of allocating a wireless resource for an SDMA communication, which can reduce waste of the wireless resource and achieve excellent performance by simultaneously using the signal relay technology and the beam-forming technology and efficiently controlling the two technologies is needed.